\renewcommand{\thetable}{\arabic{table}}

\clearpage 

%--- kai --- 
% china 1.41 
% eur   0.62  
% rus   0.39
% usa   0.87
% aus   0.93
% other 1.00
% mean  0.96

%
\begin{table}[t]
% 
%
\caption{Regionally averaged annual mean radon emission flux over land in the merged radon flux map.
%Grid boxes with radon emission flux less than 0.01~atom~cm$^{-2}$~s$^{-1}$ are excluded when calculating 
%the average value.  
% 
%
\label{tab:emisavg}} \vskip4mm \centering\small \scalebox{0.75}[0.75]{
% 
%
\begin{tabular}{l l}
% 
%
\tophline
%
 Region & Emission Flux \\
        & (atom~cm$^{-2}$~s$^{-1}$) \\
%
\middlehline
%
 Europe       & 0.62 \\ 
 China        & 1.41 \\ 
 Russia       & 0.39 \\ 
 USA          & 0.87 \\ 
 Australia    & 1.02 \\ %0.93 in mine 
 Others       & 0.92 \\ 
 Global (between 60$^{\circ}$S and 60$^{\circ}$N)      & 0.96 \\ 
%
%
%
\bottomhline
\end{tabular}}
\end{table}

%---------------------- table: radon measurements -------------------------
% 
%
\begin{table*}[t]
% 
%
\caption{Detailed information about the surface radon measurements used in this study. 
In the "Reference" column, 
DWD stands for Deutscher Wetterdienst (German Weather Service), 
BFS for Federal Office for Radiation Protection of Germany, 
IPSL for Institut Pierre-Simon Laplace, 
EML for DOE/Environmental Measurements Laboratory, and 
NCAR/EOL for National Center for Atmospheric Research Earth Observing Laboratory.
The right most column categorizes the data source: 
I: Data already used for model evaluation in \citet{zhang:2008b};  
II: Data of the period 1955--1987 compiled by J. Feichter; 
III: New measurements from observers;
IV: New data from recent publications.  
Location of these site are also shown in Fig.~\ref{fig:location}.
% 
%
\label{tab:sites}} \vskip4mm \centering\small \scalebox{0.75}[0.75]{
% 
%
\begin{tabular}{ l r l l l l}
% 
%
\tophline
% 
%
 Site & Location & Type & Period & Reference & Note \\
% 
%
\middlehline
%
% 1. data already used for model evaluation in zhang et al. 2008
% 2. data of 1955-1987 compiled by J. Feichter. 
% 3. new data from observers  
% 4. new data from eview publications 
% 
\textbf{North America} & & & & & \\ 
 Livermore, USA    & 121$^{\circ}$48$'$W, 37$^{\circ}$42$'$N & Coastal     & 1965--1966     & \citet{lindeken:1966}   & I  \\ %1965.05--1966.08  
 Socorro, USA            & 106$^{\circ}$54$'$W, 34$^{\circ}$06$'$N & Continental & 1951--1956     & \citet{wilkening:1959}  & I  \\
 Cincinnati, USA         &  84$^{\circ}$30$'$W, 39$^{\circ}$08$'$N & Continental & 1959--1963     & \citet{gold:1964}       & I  \\
 Bermuda Island, USA     &  64$^{\circ}$39$'$W, 32$^{\circ}$22$'$N & Oceanic     & 1991--1996     & EML \citep{hutter:1995} & I  \\
 Chester, USA            &  72$^{\circ}$30$'$W, 41$^{\circ}$24$'$N & Continental & 1977--1983     & \citet{jacob:1990}      & II \\
%New York          &  73$^{\circ}$54$'$W, 40$^{\circ}$42$'$N & Continental & 1982--1988     & \citet{fisenne:1996}    & II \\
 Sterling, USA           &  77$^{\circ}$25$'$W, 38$^{\circ}$57$'$N & Continental & 1966--1967     & \citet{hosler:1968}     & II \\ 
 Washington D.~C., USA   &  76$^{\circ}$54$'$W, 38$^{\circ}$54$'$N & Coastal     & 11 years       & \citet{lockhart:1964}   & II \\ 
 Grifon , USA            &  77$^{\circ}$40$'$W, 35$^{\circ}$35$'$N & Continental & 1997           & NCAR/EOL; \citet{bakwin:1995}  & III \\  
%Mauna Loa         & 155$^{\circ}$35$'$W, 19$^{\circ}$32$'$N & Oceanic     & 1991--1996     & EML \citep{hutter:1995} & \\
% 
%
\middlehline
%
%
\textbf{Europe} & & & & & \\
 Hohenpeissenberg, Germany &  11$^{\circ}$01$'$E, 47$^{\circ}$48$'$N & Continental & 1999--2005     & DWD \citep{zellweger:2006}  & I  \\ 
 Mace Head, Ireland        &  09$^{\circ}$54$'$W, 53$^{\circ}$18$'$N & Coastal     & 1995--2001     & IPSL \citep{ramonet:2003}   & I  \\
 Helsinki,  Finland        &  25$^{\circ}$00$'$E, 60$^{\circ}$05$'$N & Continental & 1968           & \citet{mattsson:1970b}      & II \\  
 Joensuu,   Finland        &  29$^{\circ}$27$'$E, 62$^{\circ}$21$'$N & Continental & 1968           & \citet{mattsson:1970b}      & II \\  
 Kevo,      Finland        &  27$^{\circ}$00$'$E, 69$^{\circ}$00$'$N & Continental & 1968           & \citet{mattsson:1970b}      & II \\  
 Nurmijarvi,Finland        &  24$^{\circ}$24$'$E, 60$^{\circ}$36$'$N & Continental & 1967--1968     & \citet{mattsson:1970b}      & II \\  
 Rovaniemi, Finland        &  25$^{\circ}$24$'$E, 66$^{\circ}$18$'$N & Continental & 1968           & \citet{mattsson:1970b}      & II \\ 
 Vaasa,     Finland        &  21$^{\circ}$21$'$E, 63$^{\circ}$04$'$N & Continental & 1968           & \citet{mattsson:1970b}      & II \\  
 Pallas,    Finland        &  24$^{\circ}$20$'$E, 67$^{\circ}$59$'$N & Continental & 1996-2002      & \citet{hatakka:2003}        & II \\ 
 Paris,     France         &   2$^{\circ}$12$'$E, 48$^{\circ}$31$'$N & Continental & 1955--1960     & \citet{servant:1961}        & II \\ 
 Saclay,    France         &   2$^{\circ}$04$'$E, 48$^{\circ}$13$'$N & Continental & 1956--1960     & \citet{servant:1961}        & II \\  
 Gif-sur-Yvette, France    &   2$^{\circ}$05$'$E, 48$^{\circ}$25$'$N & Continental & 2002--2010.07  & \citet{yver:2009}           & III\\  
%Toulouse,  France         &   1$^{\circ}$15$'$E, 43$^{\circ}$22$'$N & Continental & 2 years        & \citet{lambert:1982}        & II \\  
%Moscow,    Russia         &  37$^{\circ}$25$'$E, 55$^{\circ}$25$'$N & Continental & 1964           & \citet{lambert:1982}        & II \\
 Freiburg,         Germany &   7$^{\circ}$51$'$E, 48$^{\circ}$00$'$N & Continental & 1999--2001     & BFS; \citet{xia:2010}       & III\\ 
 Schauinsland,     Germany &   7$^{\circ}$54$'$E, 47$^{\circ}$54$'$N & Continental & 1999--2001     & BFS; \citet{xia:2010}       & III\\
 Milan, Italy              &   9$^{\circ}$11$'$E, 45$^{\circ}$28$'$N & Continental & 1997--1998     & \citet{sesana:2006}         & IV \\ 
 Erba, Italy               &   9$^{\circ}$13$'$E, 45$^{\circ}$49$'$N & Continental & 1997--1998     & \citet{sesana:2006}         & IV \\ 
 Heidelberg,       Germany &   8$^{\circ}$54$'$E, 49$^{\circ}$24$'$N & Continental & 1998           & \citet{chevillard:2002}     & IV \\  
 Zingst,  Germany          &  12$^{\circ}$42$'$E, 54$^{\circ}$24$'$N & Continental & 1998           & \citet{chevillard:2002}     & IV \\
%Jungfraujoch, Switzerland &   7$^{\circ}$59$'$E, 46$^{\circ}$33$'$N & Coastal     & 1998           & \citet{chevillard:2002}     & IV \\ 
 Lutjewad, Netherlands     &   6$^{\circ}$21$'$E, 53$^{\circ}$24$'$N & Coastal     & 2006--2008     & \citet{laan:2009}           & IV \\ 
% 
%
\middlehline
%
%
\textbf{Asia} & & & & & \\ 
 Gosan, Korea              & 126$^{\circ}$12$'$E, 33$^{\circ}$18$'$N & Oceanic     & 2001           & \citet{zahorowski:2005} & I  \\ 
 Hong Kong, China          & 114$^{\circ}$18$'$E, 22$^{\circ}$12$'$N & Coastal     & 2001           & \citet{zahorowski:2005} & I  \\ 
 Beijing,   China          & 116$^{\circ}$12$'$E, 39$^{\circ}$36$'$N & Continental & 1988--1992     & \citet{jin:1998}        & I  \\ 
 Huhehaote, China          & 111$^{\circ}$42$'$E, 40$^{\circ}$48$'$N & Continental & 1988--1992     & \citet{jin:1998}        & I  \\ 
 Changchun, China          & 125$^{\circ}$12$'$E, 43$^{\circ}$54$'$N & Continental & 1988--1992     & \citet{jin:1998}        & I  \\
 Nanjing,   China          & 118$^{\circ}$48$'$E, 32$^{\circ}$00$'$N & Continental & 1988--1992     & \citet{jin:1998}        & I  \\
 Xi'an,     China          & 108$^{\circ}$54$'$E, 34$^{\circ}$18$'$N & Continental & 1988--1992     & \citet{jin:1998}        & I  \\
 Wuhan,     China          & 114$^{\circ}$06$'$E, 30$^{\circ}$36$'$N & Continental & 1988--1992     & \citet{jin:1998}        & I  \\
 Guiyang,   China          & 106$^{\circ}$42$'$E, 26$^{\circ}$36$'$N & Continental & 1988--1992     & \citet{jin:1998}        & I  \\
 Shanghai,  China          & 121$^{\circ}$24$'$E, 31$^{\circ}$12$'$N & Coastal     & 1988--1992     & \citet{jin:1998}        & I  \\ 
 Fuzhou,    China          & 119$^{\circ}$18$'$E, 26$^{\circ}$06$'$N & Coastal     & 1988--1992     & \citet{jin:1998}        & I  \\  
 Bombay, India             &  72$^{\circ}$48$'$E, 18$^{\circ}$54$'$N & Coastal     & 1966--1976     & \citet{mishra:1980}     & I  \\
%Pathankot, India          &  10$^{\circ}$59$'$W, 47$^{\circ}$25$'$N & Continental & 2003--2004     & \citet{sahota:2005}     & IV \\ %2003.11-2004.01  
% 
%
\middlehline
%
%
\textbf{South America, Australia, Africa} & & & & & \\
 Para, Brazil              &  55$^{\circ}$00$'$W, 02$^{\circ}$54$'$S & Continental & 2000--2004     & \citet{martens:2004}    & I  \\ %2000.07--2004.12
 Chacaltaya, Bolivia       &  67$^{\circ}$36$'$W, 15$^{\circ}$42$'$S & Continental & 1958--1960     & \citet{lockhart:1960}   & II \\
 Rio de Janeiro, Brazil    &  43$^{\circ}$12$'$W, 23$^{\circ}$00$'$S & Continental & 1958--1960     & \citet{lockhart:1960}   & II \\
 Cape Grim, Tasmania       & 144$^{\circ}$41$'$E, 40$^{\circ}$40$'$S & Coastal     & 2000--2001     & \citet{zahorowski:1999} & I  \\ 
 Cape Point, South Africa  &  18$^{\circ}$30$'$W, 34$^{\circ}$21$'$N & Coastal     & 2000--2001     & \citet{brunke:2004}     & III\\ 
% 
%
\middlehline
%
%
\textbf{Remote ocean and polar regions} & & & & & \\
 Amsterdam Island, France  &  77$^{\circ}$32$'$E, 37$^{\circ}$47$'$S & Oceanic & 15 years       & \citet{polian:1986}           & II \\ 
 Crozet Island,    France  &  51$^{\circ}$51$'$E, 46$^{\circ}$27$'$S & Oceanic & 15 years       & \citet{polian:1986}           & II \\ 
 Kerguelen,        France  &  70$^{\circ}$18$'$E, 49$^{\circ}$18$'$S & Oceanic & 15 years       & \citet{polian:1986}           & II \\ 
 Mauna Loa,        USA     & 155$^{\circ}$35$'$W, 19$^{\circ}$32$'$N & Oceanic     & 2001           & \citet{zahorowski:2005} & IV  \\
 Macquarie Island, Austrilia   & 159$^{\circ}$00$'$E, 54$^{\circ}$30$'$S & Oceanic     & 1987       & \citet{downey:1990}       & IV \\ 
 Mawson, Antarctica            &  62$^{\circ}$54$'$E, 67$^{\circ}$42$'$S & Coastal     & 1999--2000 & \citet{whittlestone:2000} & IV \\
 Dumont d'Urville, Antarctica  & 140$^{\circ}$00$'$E, 66$^{\circ}$00$'$S & Coastal     & 1978--1979 & \citet{heimann:1990}      & I \\ 
%
%
%
\bottomhline
\end{tabular}}
\end{table*}
